Sanitary napkins having pressure sensitive adhesive means for attachment of the napkin to a supporting undergarment have received substantial consumer acceptance over the past several years. These napkins are generally characterized by parallel longitudinal sides and extending tab areas at each end thereof.
These napkins typically have an absorbent pad, a fluid permeable cover and a fluid impermeable baffle. The baffle may be attached adhesively or it may be fused to the wrap or to the absorbent pad itself. The pressure sensitive adhesive utilized for garment attachment is applied either directly to the baffle or, if the outer wrap encircles the baffle it may be applied to that component and, as taught in U.S. Pat. No. 3,674,595 may actually serve to adhere the wrap to the baffle and attach the overlapping ends of the wrap.
Regardless of whether the adhesive is applied to the wrap or to the baffle, the particular placement of the adhesive along the undergarment-facing side of the pad determines to a large extent, both the effectiveness of the adhesive attachment and the comfort of the napkin to the user when the user is active.
A variety of configurations for adhesive placement have been taught in the past, see for example, U.S. Pat. No. 3,454,008 which describes adhesive placement at the ends of the napkin and U.S. Pat No. 3,674,595 which discloses a napkin having adhesive lines parallel to but recessed slightly inward from the longitudinal margins of the napkin. This slightly inwardly recessed configuration which is parallel to the longitudinal edges, has achieved wide consumer acceptance as being extremely effective in maintaining the attachment of the napkin to the undergarment.
Recently, however, sanitary napkins have been introduced which have inwardly arcuate edges along each of the longitudinal sides. This configuration conforms to a greater degree to the geometry of the perineal area and, as a result, is more comfortable for the wearer. Sanitary napkins with these inwardly arcuate configurations are generally of the so-called panty liner type. These napkins are designed to be substantially less bulky and are specifically adapted for use either with a tampon or for days when there is only light menstrual flow or other slight vaginal discharge.
The panty liner type of sanitary napkin, because of its reduced bulk, has increased flexibility and is much more likely to contort during activity by the wearer. Where napkins of this configuration are attached by twin adhesive lines parallel to each other, there is a substantial variance in the distance between the edge of the napkin at the center of the arc and at the ends of the cutout area. The distance between the adhesive lines and the ends of the cutout area is substantially greater than that at the deepest inward portion of the arc and, during normal use, this free, unattached portion of the napkin may be folded back onto itself at the bottom and actually adhere to the adhesive designed for attachment to the undergarment at each end of the panty liner. In addition, the non-adhered free ends at the napkin edges may produce substantial chafing due to the flexibility and freedom of movement in these locations.